//count_if example
#include <iostream>     //std::cout
#include <algorithm>    //std::count_if
#include <vector>       //std::vector
using namespace std;
bool IsOdd(int i){ return((i%2)==1);}

int main(){
    std::vector<int> myvector;
    for(int i = 1;i<10;i++) myvector.push_back(i);//myvector: 1 2 3 4 5 6 7 8 9 

    int mycount = count_if(myvector.begin(),myvector.end(),IsOdd);
    cout << "myvector contains " << mycount << " odd values.\n";
    return 0;
}